SIST EN 61204:1999
(Main)Low-voltage power supply devices, d.c. output - Performance characteristics
Low-voltage power supply devices, d.c. output - Performance characteristics
Describes a method of specifying requirements for low-voltage power supply devices (including switching types) providing d.c. output(s) up to 200 V d.c. at a power level up to 30 kW, operating from a.c. or d.c. source voltages of up to 600 V. The devices are for use within class I equipment or for free-standing operation when used with adequate electrical and mechanical protection, except for medical applications and toys, where special considerations apply.
Stromversorgungsgeräte für Niederspannung mit Gleichstromausgang - Eigenschaften
Dispositifs d'alimentation à basse tension à sortie en courant continu - Caractéristiques de fonctionnement
Décrit une méthode de prescription des caractéristiques pour les alimentations basse tension (y compris les alimentations à découpage) jusqu'à 200 V c.c. à la sortie et de puissance inférieure à 30 kW, opérant à partir d'une tension de source continue ou alternative limitée jusqu'à 600 V. Les unités sont prévues pour utilisation à l'intérieur d'équipement de classe 1 ou en opération autonome avec des protections électriques et mécaniques adéquates, à l'exception des applications médicales et des jouets où des considérations spéciales sont applicables.
Low-voltage power supply devices, d.c. output - Performance characteristics and safety requirements (IEC 61204:1993)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61204:1999
01-julij-1999
Low-voltage power supply devices, d.c. output - Performance characteristics and
safety requirements (IEC 61204:1993)
Low-voltage power supply devices, d.c. output - Performance characteristics
Stromversorgungsgeräte für Niederspannung mit Gleichstromausgang - Eigenschaften
Dispositifs d'alimentation à basse tension à sortie en courant continu - Caractéristiques
de fonctionnement
Ta slovenski standard je istoveten z: EN 61204:1995
ICS:
29.160.40 (OHNWULþQLDJUHJDWL Generating sets
29.200 8VPHUQLNL3UHWYRUQLNL Rectifiers. Convertors.
6WDELOL]LUDQRHOHNWULþQR Stabilized power supply
QDSDMDQMH
SIST EN 61204:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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NORME CEI
INTERNATIONALE IEC
1204
INTERNATIONAL
Première édition
STANDARD
First edition
1993-02
Dispositifs d'alimentation à basse tension,
à sortie en courant continu -
Caractéristiques de fonctionnement
et prescriptions de sécurité
Low-voltage power supply devices,
d.c. output -
characteristics and
Performance
safety requirements
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© CEI 1993
publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
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in writing from the publisher.
les microfilms, sans raccord écrit de l'éditeur.
Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé Genève, Suisse
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Pour prix, voir catalogue en vigueur •
For price, see current catalogue
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- 3 -
1204 ©IEC: 1993
CONTENTS
Page
FOREWORD 7
INTRODUCTION 9
Clause
11
1 General
11
1.1 Scope and object
11
1.2 Normative references
13
1.3 Definitions
Presentation of performance characteristics 15
2
15
3 Performance
15
3.1 Rated outputs and total output power
19
3.2 Ambient operating temperature range
21
3.3 Ambient storage and transit temperature range
21 3.4 Source voltage and frequency
23
3.5 Source current
23
3.6 Source effect (source regulation)
25 Load effect (load regulation) 3.7
Output voltage tolerance (intrinsic error) - fixed outputs 25
3.8
25
Adjustability of output voltage 3.9
27
3.10 Periodic and random deviation
27
3.11 Interaction effects (cross regulation)
3.12 Temperature coefficient 29
29
3.13 Hold-up time (turn-off decay time)
29
3.14 Start-up time (turn-on delay time)
31
3.15 Turn-on (turn-off) overshoot
31
3.16 Transient response to load current changes
33
3.17 Output overvoltage protection
33
3.18 Output overcurrent protection
3.19 Mean time between failures (MTBF) 35
35
4 Requirements for safety
35
4.1 General
35
4.2 Creepage distances, clearances and distances through insulation
4.3 Electric strength 35
35
4.4 Earth leakage current
35
4.5 Flammability
37
4.6 Thermal requirements
37
4.7 Protective devices
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1204 ©IEC: 1993 — 5 —
Page
Clause
37
5 Interference requirements
37
5.1 Noise level
37
5.2 Conducted EMI
5.3 Radiated EMI (magnetic component) 37
Input transient voltage 39
5.4
39
6 Additional requirements
39
6.1 Remote programming (remote control)
39
6.2 Remote sensing
41
6.3 Mechanical characteristics
41 6.4 Series operation
6.5 Parallel operation 41
41
Monitoring and control signals 6.6
7 Test requirements 41
7.1 41
General
43
7.2 Environmental tests
Miscellaneous requirements 43
8
43
8.1 Markings and instructions
ANNEXES
45
A Periodic and random deviation test methods
51
B Output overvoltage protection
53
C Overcurrent protection characteristics
D Parallel operation 55
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1204 ©IEC: 1993 - 7 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
LOW-VOLTAGE POWER SUPPLY DEVICES,
D.C. OUTPUT - PERFORMANCE CHARACTERISTICS
AND SAFETY REQUIREMENTS
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
3) They have the form of recommendations for international use published in the form of standards, technical
reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
This International Standard IEC 1204 has been prepared by sub-committee 22E: Stabi-
lized power supplies, of IEC technical committee 22: Power electronics.
The text of this standard is based on the following documents:
DIS Report on Voting
22E(CO)24 22E(CO)26
Full information on the voting for the approval of this standard can be found in the repo rt
on voting indicated in the above table.
Annexes A to D form an integral pa rt of this standard.
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1204 © I EC: 1993 - 9 -
INTRODUCTION
This International Standard, based on the British Standard BS6688: 1986, has been
reworked and extended to take into account existing and forthcoming IEC standards. With
regard to safety, there was close collaboration with IEC technical committee 74, working
group 6: Safety requirements for power supplies.
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1204 © IEC: 1993 - 11 -
LOW-VOLTAGE POWER SUPPLY DEVICES,
D.C. OUTPUT - PERFORMANCE CHARACTERISTICS
AND SAFETY REQUIREMENTS
1 General
1.1
Scope and object
This international Standard describes a method for specifying requirements for low-voltage
power supply devices (including switching types) providing d.c. output(s) up to 200 V d.c.
at a power level of up to 30 kW, operating from a.c. or d.c. source voltages of up to 600 V.
The devices are for use within class I equipment or for free-standing operation when used
with adequate electrical and mechanical protection.
This standard is intended to cover all types of a.c. or d.c. driven units with any number of
outputs including power supply devices used in military, industrial, telecommunications
and commercial applications. Special considerations apply for medical applications and
toys.
It permits to specify a power unit to meet a particular application by the specification of
parameters at required performance levels, to establish the essential definitions related to
ormance. These levels
this type of equipment, and to establish a selection of levels of pe rf
are carefully graded to enable manufacturers and users to select and specify a range of
power supply devices suitable for their application.
1.2 Normative references
The following normative documents contain provisions which, through reference in this
text, constitute provisions of this International Standard. At the time of publication, the
rties
editions indicated were valid. All normative documents are subject to revision, and pa
to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated
below. Members of IEC and ISO maintain registers of currently International Standards.
IEC standard voltages
IEC 38: 1983,
IEC 68: Environmental testing
Environmental testing - Part 2: Tests - Test A: Cold
IEC 68-2-1: 1990,
IEC 68-2-2: 1974, Environmental testing - Part 2: Tests - Test B: Dry heat
IEC 68-2-3: 1985, Environmental testing - Pa rt 2: Tests - Test Ca: Damp heat, steady
state
IEC 68-2-6: 1982, Environmental testing - Pa rt 2: Tests - Test Fc and guidance: Vibration
(sinusoidal)
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1204 © IEC: 1993 - 13 -
IEC 68-2-27: 1987, Environmental testing - Part 2: Tests - Test Ea and Guidance: Shock
IEC 68-2-29: 1987, Environmental testing - Part 2: Tests - Test Eb and Guidance: Bump
IEC 478: Stabilized power supplies, d.c. output
IEC 478-1: 1974, Stabilized power supplies, d.c. output - Part 1: Terms and definitions
Stabilized power supplies, d.c. output - Part 2: Rating and performance
IEC 478-2: 1986,
Stabilized power supplies, d.c. output - Part 3: Reference levels and
IEC 478-3: 1989,
measurement of conducted electromagnetic interference (EMI)
Stabilized power supplies, d.c. output - Pa rt 4: Tests other than
IEC 478-4: 1976,
radio-frequency interference
Stabilized power supplies, d.c. output - Part 5: Measurement of the
IEC 478-5: 1993,
magnetic component of the reactive near field
IEC 651: 1979, Sound level meters
IEC 664-1: 1992, Insulation co-ordination for equipment within low-voltage systems -
Part 1: Principles, requirements and tests
IEC 721: Classification of environmental conditions
IEC 721-3-1: 1987, Classification of environmental conditions - Part 3: Classification of
groups of environmental parameters and their severities. Storage
IEC 721-3-2: 1985, Classification of environmental conditions - Part 3: Classification of
rt
groups of environmental parameters and their severities. Transpo
Electromagnetic compatibility for industrial-process measurement and control
IEC 801:
equipment
IEC 801-4: 1988, Electromagnetic compatibility for industrial-process measurement and
control equipment - Part 4: Electrical fast transient/burst requirements
IEC 950: 1991, Safety of information technology equipment, including electrical business
equipment
MIL-HDBK-217E: 1974, Reliability prediction of electronic equipment
1.3 Definitions
For the purpose of this International Standard the definitions given in IEC 950 and IEC 478-1
apply, except where redefined in this standard.
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1204 © IEC: 1993 - 15 -
2 Presentation of performance characteristics
The performance characteristics are detailed in 3.1 to 8.1 and are in accordance with the
performance criteria listed in table Ill of IEC 478-2.
The performance figure defines the maximum change (not typical) in the measured
quantity which may be either positive or negative unless specified otherwise. Note that this
implies that a 1 % change may mean a maximum difference of 2 % between quantities
measured on a number of units.
ormance parameters are measured at 25 °C unless otherwise stated.
The pe rf
rformance characteristics shall be as stated in table Ill of IEC 478-2.
Tests relating to pe
Where a specific instruction appears to conflict with that indicated in table I or Ill, this
standard shall take precedence.
The pe rformance characteristics presentation of table I illustrates a typical application.
The indication of the present IEC publication subclause numbering is mandatory. The
ormance figure indicates that no requirements exist. Indicating the
absence of a pe rf
performance letter coding within brackets is optional.
3 Performance
3.1 Rated outputs and total output power
ormance levels of the unit shall be stated for each parameter.
The output voltages and pe rf
For a multiple output power supply, performance levels shall be indicated for each output.
The manufacturer/(user) shall confirm/(specify) that the variations in output voltage of the
unit comply with the stated limits given in 3.2 to 3.18, as appropriate, under the least
favourable combination of source voltage, load and temperature at the stated output level
of the unit.
The manufacturer/(user) shall confirm /(specify) the minimum load value for the controlling
output in a multiple output power supply that is required to maintain any other parameter
within the specification. The nature of each output and its polarity, if fixed, shall also be
stated or specified.
If the loads are defined by the customer, then the rated value of these loads shall be used
in performance measurements. In all other cases, the output to be measured shall be at
maximum, other outputs at 50 % of their rated output load, and voltage input of the power
supply shall be at rated value.
The manufacturer/(user) shall confirm/(specify) the total output power at one of the
preferred high ambient operating temperatures of 3.2.
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1204 © IEC: 1993 - 17 -
Table 1 - Performance characteristics presentation
IEC 1204
Clause/subclause
Main output: 5 V 150 A
Rated outputs
15 A
3.1 Aux. 1: 12 V
Aux. 2: 24 V 8 A
Total output power 1 000 W at 50 °C
Ambient operating temperature range Low: 0 °C (D)
3.2 High: 50 °C (D)
(70 °C with de-rating of 2,5 %/°C above
50 °C) Forced air cooled, internal fan
Ambient storage temperature range –40 °C to +85 °C (A)
3.3
Source voltage and frequency Low: 88 V to 132 V (C)
High: 176 V to 264 V (C)
3.4
Frequency range: 48 Hz to 63 Hz
Source current
True R.M.S 20 A at 88 V input; 10 A at 176 V
Peak repetitive 50 A at 88 V input; 25 A at 176 V
30 A
3.5 Peak inrush
0,65
Harmonic distortion
Power factor 0,65
0,70
Efficiency
Auxiliary output
Main output
3.6 Source regulation 0,1 % (A) 0,1 % (A)
0,2 % (A) 0,2 % (A)
3.7 Load regulation
0 to 100 % (A) 0 to 100 % (A)
Load change
3.8 Intrinsic error N/A N/A
Adjustability of voltage output
3.9 Span 80% to 120% 80% to 120%
Resolution 1 % 1 %
Periodic and random deviation
3.10 a) Source frequency 0,1 % (A) 0,1 % (A)
0,5 % (A) 0,5 % (A)
b) Switching frequency
(B)
c) Total (30 MHz) 1 % (B) 1 %
0,2 % (A) 0,2 % (A)
3.11 Cross regulation
0 to 100 % (A)
Load change 0 to 100 % (A)
0,02 %/°C (B) 0,02 %/°C (B)
3.12 Temperature coefficient
3.13 Hold-up time 20 ms (A) N/A
1 s (C) 1 s (C)
3.14 Start-up time
(continued on page 19)
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- 19 -
1204 © IEC: 1993
Table 1 - Performance characteristics presentation (continued)
IEC 1204
Clause/subclause
Main output Auxiliary output
None (A)
Turn-on (turn-off) overshoot None (A) 3.15
3.16 Transient response to load
current changes
(B) –
Voltage deviation 5 %
1 ms (A) Recovery time
50 % to 100 % (D) –
Load change
110 % to 130 % (C) (E)
Output overvoltage protection
3.17
(B)
Electronic inhibit
Output overcurrent protection Constant current (A)
3.18
65 000 h MIL-HDBK-217E, 25 °C, Gb
3.19 Mean-time between failures
Protection class: I
4 Requirements for safety
Overvoltage category: II
Pollution degree: 2
IEC 478-3, curve A
5.2 Conducted EMI
2 kV (D)
5.4 Input transient withstand voltage
Resistance (A) and
6.1 Remote programming
voltage programming (B)
500 mV (A)
6.2 Remoting sensing
Mechanical characteristics 203 mm x 127 mm x 300 mm
6.3
6.4 Series operation 250 V
Equal current sharing (A)
6.5 Parallel operation
Ambient operating temperature range
3.2
The operating temperature range of the unit shall be stated and specified in one of the
following preferred ranges. The manufacturer shall confirm that the power supply is
capable of continuous operation without derating at the maximum temperature stated, at
maximum rated power output, and under the least favourable conditions in the convection
cooled (free-air) environment up to 2 000 m. Derating of output current and power
at elevated temperatures shall be clearly stated. If the power supply is intended for forced
air or conduction cooling, the operating conditions shall be clearly specified and the
devices tested under these cooling conditions.
---------------------- Page: 11 ----------------------
1204 © IEC: 1993 - 21 -
The ambient temperature is defined as the final steady state temperature with the power
supply dissipating maximum power, measured 50 mm below the power supply for
convection cooling or at the air intake for forced-air cooling.
Low A -40 °C High A +85 °C
B -25 °C B +70 °C
C +55 °C
C -10 °C
D 0 °C D +50 °C
E +40 °C
E +5 °C
3.3 Ambient storage and transit temperature range
The manufacturer shall confirm that the unit complies with a storage and transit
temperature range of:
A -40 °C to +85 °C
B -25 °C to +70 °C
If pre-conditioning is required before use, due to the danger of condensation, the
manufacturer shall state clearly what action needs to be taken.
The relative humidity for storage and transit shall be coded according to IEC 721-3-1 and
IEC 721-3-2, respectively.
3.4 Source voltage and frequency
The range of source values acceptable by the power supply shall be stated and specified
as one or more of the preferred values given below.
The definitions of IEC 38 apply.
Preferred source voltage ranges
Single-phase alternating current (a.c.)
A Wide range 85 V to 264 V
Low range B 85 V to 132 V
88 V to 132 V
C
D 93Vto 132V
E 90Vto 110V
High range B 170 V to 264 V
C 176 V to 264 V
D 187 V to 264 V
E 195 V to 264 V
F 207 V to 253 V
A 48 Hzto440Hz
Frequency range
B 48Hzto 63Hz
These values are ranges which include the tolerance. If manual range change is required,
this shall be clearly stated.
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1204 © IEC: 1993
Three-phase alternating current (a.c.)
The values stated in IEC 38 are preferred for three-phase a.c. networks.
Direct current (d.c.)
The values stated in IEC 38 are preferred for direct current (d.c.).
Other values and ranges are acceptable but should be clearly stated and agreed between
the customer and supplier. Alternatively, the nominal input voltage and tolerance may be
stated.
3.5 Source current
The following quantities shall be stated both under nominal and under least favourable
conditions:
a) r.m.s. source current' ;
peak repetitive source current (a.c. sources only);
b)
c) peak inrush current2;
the harmonic distortion factor (THD) of the source current waveform;
d)
power factor (input W/input VA) ' (a.c. sources only);
e)
f) efficiency.
If the least favourable condition is at other than maximum load, the actual load shall be
stated.
Compliance with the stated performance shall be checked by inspection and in
accordance with section twelve of IEC 478-4.
3.6 Source effect (source regulation)
The regulation for the specified range of source voltage and frequency, with each output
loaded to 50 % of maximum load at its specified output voltage, shall be stated and speci-
fied as one of the following preferred values:
A 0,1 %
B 0,2 %
C 0,5 %
D 1%
E Unregulated
Compliance with the stated performance shall be checked by inspection and in
accordance with section two of IEC 478-4.
-sinusoidal
Care should be taken that measuring instruments give true r.m.s. readint in the presence of non
'
waveforms.
In measuring the peak inrush current, the charging current into EMI suppression capacitors is disregarded
2
in the first millisecond after switch-on.
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1204 © IEC: 1993 - 25 -
3.7 Load effect (load regulation)
The load regulation at the specified load range and least favourable source voltage for
each output shall be stated and specified from the following preferred values:
Load regulation Load change
A A 0to100%
0,2 %
B 0,5 % B 10to100%
C 1 % C 25 to 100%
D 5 % D 50to100%
E 10 %
If the regulation curve is non-linear it is recommended that a graph, showing the
relationship between the measured quantities, shall be given.
The test shall be performed at two different load settings as follows:
case 1 - all outputs at 100 % of full load, unless this exceeds the total power rating
when case la should be used;
case la - all outputs other than the one where the load is changed, at 50 % of full
load, or at an equal percentage load to achieve full power;
case 2 - all outputs, other than the one where the load is changed, at minimum load.
Compliance with the stated performance shall be checked by inspection and in
accordance with section one of IEC 478-4.
3.8 Output voltage tolerance (intrinsic error) - fixed outputs
The output voltage tolerance at nominal source voltage and at half the rated load for each
output shall be stated in such a way as to comply with one of the following preferred
values:
A 0,5 %
1 %
B
2 %
C
D 5 %
E 10 %
Compliance with the stated performance shall be checked by inspection, using the test
circuit measurement of figure 6 of IEC 478-4.
3.9 Adjustability of output voltage
The span and resolution of each adjustable output shall be stated under nominal source
and half-rated load conditions.
If adjusting one output will affect another, this shall be stated.
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1204 © IEC: 1993 - 27 -
3.10 Periodic and random deviation
Ripple and noise peformance for each output shall be stated and specified as one of the
following preferred values:
A 0,5 % peak-to-peak
B 1 % peak-to-peak
2 % peak-to-peak
C
D 5 % peak-to-peak
E 10 % peak-to-peak
Periodic and random variations shall be given for the following three bands:
a) low-frequency noise:
source frequency and its harmonics only (a.c. sources only);
b) switching noise:
switching frequency and its harmonics only;
total, including spikes (using measuring equipment with sufficient bandwidth).
c)
Compliance with the stated performance shall be checked in accordance with the methods
set out in annex A. It should be noted, that this method and definition is different to that
used in IEC 478-4.
If special weighting is applicable in some applications, such as telecommunications, the
measuring methods and detailed results shall be stated in addition to the above.
Interaction effects (cross regulation)
3.11
The effect on the voltage of each output resulting from a change in the loading of other
outputs in a multiple output power supply, for the specified load ranges shall be stated and
specified to comply with one of the following preferred values:
Load change
Cross regulation
A 0%to100%
A 0,2 %
B 10%to100%
B 2 %
25%to100%
C 5 % C
D D 50%to100%
10
E 20 %
The interaction effect shall take account of the following two conditions:
case 1 - all outputs at 100 % of full load, unless this exceeds the total power rating
when case 1 a should be used;
case la - all outputs other than the one where the load is changed, at 50 % of full
load, or at an equal percentage load to achieve full power;
2 - all outputs, other than the one where the load is changed, at minimum
case
load.
Compliance with the stated performance shall be checked by inspection and in
accordance with section one of IEC 478-4.
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1204 © IEC: 1993 - 29 -
3.12 Temperature coefficient
The temperature coefficient shall be stated and specified as one of the following preferred
values:
A 0,01 %/°C
B 0,02 %/°C
C 0,05 %/°C
In applications where this is a controlling parameter it is recommended that a graph be
added, showing change in output voltage against temperature.
Compliance with the stated performance shall be checked by inspection and in
accordance with section six of IEC 478-4.
Hold-up time (turn-off decay time)
3.13
Starting from nominal output voltage and power, the source voltage at minimum +10 %,
the hold-up time of the output voltage, within the specified range, shall be indicated. For
d.c. input, the actual hold-up time shall be stated. For a.c. input, hold-up time shall be
stated as one of the following periods:
A more than 20 ms from the next zero crossing; following the source voltage
outage;
B 20 ms from the next zero crossing;
C 10 ms from the next zero crossing;
D less than 10 ms.
Compliance with the stated pe rformance shall be checked by inspection under the stated
conditions, using the test circuit measurement of figure 6 of IEC 478-4.
3.14 Start-up time (turn-on delay time)
The time taken, after switch-on of the source, for the output voltage to enter the
specification band shall be stated and specified as one of the following preferred values:
A 0,1 s
B 0,2 s
C 0,5 s
D 1,0 s
E 2,0 s
F 5,0 s
Compliance with the stated performance shall be checked by inspection and in
accordance with section seven of IEC 478-4.
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31 -
1204 © IEC: 1993 -
3.15 Turn-on (turn-off) overshoot
The peak value of output overshoot at switch-on and switch-off shall be stated at nominal
input, nominal power.
A None
B 1%
C 5%
The manufacturer shall clearly state if, at any time, the output changes polarity.
The manufacturer shall confirm that no overvoltage condition exists at any load and any
source voltage between zero and the maximum specified.
If the sequence in which outputs come up or go down is controlled, the timing sequence
and loads shall be stated.
Transient response to load current changes
3.16
The transient response at the output terminals of the power supply for each output shall
be stated and should be specified as one of the preferred values given in table 2.
m, specified as a
Figures 1 and 2 illustrate the maximum output voltage deviation V
, specified as a percentage of rated valued /m.
percentage arising from a load change I X
When the output voltage returns within the load regulation band as specified in 3.7
TR is defined as the total transient recovery time of
(Vr zone C of figures 1 and 2), the time
the power supply. The characteristics in zone C can be under-damped, critically damped
or oscillatory.
Compliance with the stated performance shall be checked by inspection and in
accordance with section seven of IEC 478-4.
Im
am
Current (!X)
Current (!X
L_ y
o o
TiF
Tr
Vr
Voltage (Vm)
Voltage (Vm)
Time (TR)
so-
/EC 093193
/EC 094/93
Figure 2 - Resistive load removed at
Figure 1 - Resistive load applied at
the output terminals
the output terminals
---------------------- Page: 17 ----------------------
1204 © IEC: 1993 - 33 -
Table 2 - Preferred transient response
Voltage deviation Vm Recovery time TR Load change IX
A 2% A 1 ms A 100%to0%; 0%to100 %
10
B 5% B 5ms B 100 %to10 %; %to100%
C 10% C 20ms C 100 % to25%; 25%to100%
D 20% D 50ms D 100%to50%; 50%to100%
NOTE - The method of measurement should take account of transmission line effects, reactive loads,
d//dt, etc.
r
The rise time and fall time of load current changes T and Tf should be less than one-tenth
of the specified recovery time TR.
3.17 Output overvoltage protection
If overvoltage protection against internally generated faults of the power supply is
provided, it shall be specified for each output and at one of the following preferred values.
The manufacturer shall confirm that the output voltage never exceeds the stated maximum
levels at any time and for any load.
A 110%to120%
B
115%to125%
C 110%to130%
D 150%max.
E None
The manufacturer/(user) shall state/(specify) whether the overvoltage protection circuit is:
A crowbar protection circuit across output;
B electronic inhibit;
C inhibit and "re-try" system.
For definitions see annex B.
The maximum continuous external supply current that can be absorbed by the power
supply shall be stated.
Compliance with the stated performance shall be checked by inspection and in
accordance with section sixteen of IEC 478-4.
3.18 Output overcurrent protection
The manufacturer shall confirm whether the overcurrent protection is:
A constant current;
B foldback current;
current trip;
C
D short-circuit proof only (not protected against continuous overloads).
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For cases A, B and C, the maximum current and the short-circuit current shall be stated. It
is recommended that this be shown in the form of a graph as given in annex C. It should
be noted that these definitions differ from those used in IEC 478-1.
Compliance with this requirement shall be checked in accordance with section one of IEC 478-4.
3.19 Mean time between failures (MTBF)
The MTBF shall be predicted at nominal input, nominal output power and at 25 °C ambient
temperature, using the component count method and internationally accepted failure rate
figures (such as those contained in MIL-HDBK-217E, ground benign conditions).
Information sources and reference conditions shall be stated.
In addition, the MTBF may be established by statistical inference following a life
expectancy test under the prescribed conditions. In such a case all results as well as the
confidence level shall be stated.
4 Requirements for safety
4.1 General
In order that the safety aspects can be correctly rated, the following shall be declared by
the manufacturer:
protection class (see 1.2.4 of IEC 950);
a)
b) overvoltage (installation) category (see 2.2.2.1.1 of IEC 664-1);
c) pollution degree (see 2.5.1 of IEC 664-1).
NOTE - The declared overvoltage category in b) is of concern in power supplies energized direc
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